The present invention relates to a material and a method for making a conductive pattern.
Transparent ITO (indium-tin oxide) electrodes are used for the fabrication of flexible LC displays, electroluminescent devices and photovoltaic cells. These electrodes are made by vacuum sputtering ITO onto a substrate. This method involves high temperatures, up to 250xc2x0 C., and therefore glass substrates are generally used. The range of potential applications is limited, because of the high fabrication costs, the low flexibility (pliability) and stretchability, due to the brittleness of the ITO layer and the glass substrate. Therefore interest is growing in all-organic devices, comprising plastic resins as a substrate and organic intrinsically conductive polymer layers as electrodes. Such plastic electronics allow the realization of low cost devices with new properties (Physics World, March 1999, p. 25-39). Flexible plastic substrates can be provided with an intrinsically conductive polymer layer by continuous roller coating methods (compared to batch process such as sputtering) and the resulting organic electrodes enable the fabrication of electronic devices with higher flexibility and a lower weight.
The production and use of intrinsically conductive polymers such as polypyrrole, polyaniline, polyacetylene, polyparaphenylene, polythiophene, polyphenylenevinylene, polythienylenevinylene and polyphenylenesulphide are known in the art.
EP-A 440 957 discloses dispersions of polythiophenes, constructed from structural units of formula (I): 
in which R1 and R2 independently of one another represent hydrogen or a C1-4-alkyl group or together form an optionally substituted C1-4-alkylene residue, in the presence of polyanions. Furthermore, EP-A-686 662 discloses mixtures of A) neutral polythiophenes with the repeating structural unit of formula (I), 
in which R1 and R2 independently of one another represent hydrogen or a C1-4-alkyl group or together represent an optionally substituted C1-4-alkylene residue, preferably an optionally with alkyl group substituted methylene, an optionally with C1-12-alkyl or phenyl group substituted 1,2-ethylene residue or a 1,2-cyclohexene residue, and B) a di- or polyhydroxy- and/or carboxy groups or amide or lactam group containing organic compound; and conductive coatings therefrom which are tempered at elevated temperature, preferably between 100 and 250xc2x0 C., during preferably 1 to 90 seconds to increase their resistance preferably to  less than 300 ohm/square.
Coated layers of organic intrinsically conductive polymers can be structured into patterns using known microlithographic techniques. In WO-A-97 18944 a process is described wherein a positive or negative photoresist is applied on top of a coated layer of an organic intrinsically conductive polymer, and after the steps of selectively exposing the photoresist to UV light, developing the photoresist, etching the intrinsically conductive polymer layer and finally stripping the non-developed photoresist with an organic solvent, a patterned layer is obtained. A similar technique has been described in 1988 in Synthetic Metals, volume 22, pages 265-271 for the design of an all-organic thin-film transistor. Such methods are cumbersome as they involve many steps and require the use of hazardous chemicals.
WO 01/88958 published on Nov. 22, 2001 discloses a method of forming a pattern of a functional material on a substrate comprising: applying a first pattern of a first material to said substrate; and applying a second functional material to said substrate and said first material, wherein said first material, said second functional material, and said substrate interact to spontaneously form a second pattern of said second functional material on said substrate, to thereby form a pattern of a functional material a substrate.
It is an aspect of the present invention to provide a process for making a conductive pattern, which does not require the use of hazardous chemicals.
It is a further aspect of the present invention to provide a material having a conductive pattern without a development step.
It is a further aspect of the present invention to provide a material having a conductive element that can be processed to a conductive pattern by a simple, convenient method which involves a low number of steps and which does not require the use of hazardous chemicals.
Further aspects and advantages of the invention will become apparent from the description hereinafter.
A conductive pattern can be realized with the materials of the present invention, which are optionally conductivity enhanced, without image-wise heating or exposure and with optionally a single wet processing step, and optional conductivity enhancement. No etching liquids or organic solvents are required. Furthermore, a conductive pattern is realized in layers xe2x89xa6500 nm thick without processing.
Aspects of the present invention are realized by a material having a conductive pattern, the material comprising a support and a conductive element, the conductive element being 500 nm thick or less and containing a polyanion and an intrinsically conductive polymer, characterized in that one surface of the conductive element is an outermost surface of the material and the other surface of the conductive element is contiguous with a patterned surface, the patterned surface consisting of at least two types of surface element, and those parts of the conductive element contiguous with a type A surface element exhibiting a surface resistance at least a factor of ten greater than those parts of the conductive element contiguous with a type B surface element.
Aspects of the present invention are also realized by a material for making a conductive pattern, the material comprising a support and a conductive element, the conductive element containing a polyanion and an intrinsically conductive polymer, characterized in that one surface of the conductive element is an outermost surface of the material, the other surface of the conductive element is contiguous with a patterned surface, the patterned surface consisting of at least two types of surface element, and those parts of the conductive element contiguous with one type of the surface elements are capable of being at least partially removed by a developer.
Aspects of the present invention are also realized by a method of making a conductive pattern on a support comprising the steps of: providing a material for making a conductive pattern as disclosed above; processing the material with a developer, thereby at least partially removing those parts of the conductive element contiguous with one type of the surface elements; and optionally treating the material to increase the electroconductivity of the material.
Further advantages and embodiments of the present invention will become apparent from the following description.
The term xe2x80x9csupportxe2x80x9d means a xe2x80x9cself-supporting materialxe2x80x9d so as to distinguish it from a xe2x80x9clayerxe2x80x9d which may be coated on a support, but which is itself not self-supporting. It also includes any treatment necessary for, or layer applied to aid, adhesion to the differentiable element.
The term conductive means having a surface resistance or 1011 xcexa9/square or less and is a generic term including both the terms antistatic and electroconductive.
The term electroconductive means having a surface resistance below 106 xcexa9/square. Antistatic materials have surface resistances in the range from 106 to 1011 xcexa9/square and cannot be used as an electrode.
The term conductive pattern means a pattern with elements which have different surface resistances.
The term intrinsically conductive polymer means organic polymers which have (poly)-conjugated xcfx80-electron systems (e.g. double bonds, aromatic or heteroaromatic rings or triple bonds) and whose conductive properties are not influenced by environmental factors such as relative humidity.
The term continuous layer refers to a layer in a single plane covering the whole area of the support and not necessarily in direct contact with the support.
The term non-continuous layer refers to a layer in a single plane not covering the whole area of the support and not necessarily in direct contact with the support.
Conductivity enhancement refers to a process in which the conductivity is enhanced e.g. by contact with high boiling point liquids such as di- or polyhydroxy- and/or carboxy groups or amide or lactam group containing organic compound optionally followed by heating at elevated temperature, preferably between 100 and 250xc2x0 C., during preferably 1 to 90 seconds, results in conductivity increase. Alternatively in the case of aprotic compounds with a dielectric constant xe2x89xa715, e.g. N-methyl-pyrrolidinone, temperatures below 100xc2x0 C. can be used. Such conductivity enhancement is observed with polythiophenes and can take place during the preparation of the outermost layer or subsequently. Particularly preferred liquids for such treatment are N-methyl-pyrrolidinone and diethylene glycol such as disclosed in EP-A 686 662 and EP-A 1 003 179.
The term removability as used in the description and claims of the present invention means mechanically removable in the absence of a liquid or removable with the application of a liquid with or without the simultaneous or subsequent use of rubbing or other mechanical removal means. The application of liquid can dissolve, swell or disperse the outermost layer according to the present invention such that removal is realized or enabled.
The term multidiazonium salt includes all compounds with at least two groups with two nitrogen atoms bonded together with a double or triple bond, such groups including xe2x80x94Nxe2x89xa1N+ and xe2x80x94Nxe2x95x90Nxe2x80x94R groups e.g. xe2x80x94Nxe2x95x90Nxe2x80x94SO3M groups.
The term resin comprising a diazonium salt means a resin with groups with two nitrogen atoms bonded together with a double or triple bond, such groups including xe2x80x94Nxe2x89xa1N+ and xe2x80x94Nxe2x95x90Nxe2x80x94R groups e.g. xe2x80x94Nxe2x95x90Nxe2x80x94SO3M groups.
The term proteinaceous means pertaining to any material having a protein base.
The material having a conductive pattern, according to the present invention, has a conductive element 500 nm or less thick contiguous with a patterned surface consisting of at least two types of surface element. Contact of these types of surface elements with the conductive element results in a lower surface resistance of those parts of the conductive element contiguous with one type of surface element than those parts of the conductive element contiguous with another type of surface element. Each type of surface element lies in the same plane, but all surface elements need not lie in the same plane.
The reason for this effect is unknown, but the effect is only observed for conductive elements with a thickness of 500 nm or less. At such thicknesses, the thinness of conductive element means that the interfacial forces between the conductive element and the patterned surface during coating and during and after drying will have a considerable effect on the properties of the electroconductive layer and hence possibly on the surface resistance thereof.
According to a first embodiment of a material having a conductive pattern, according to the present invention, the conductive pattern is an electroconductive pattern.
According to a second embodiment of a material having a conductive pattern, according to the present invention, the patterned surface is planar or non-planar. A non-planar pattern can be produced using conventional printing techniques, such as screen printing, offset printing, flexographic printing and ink jet printing, with conventional resist technology, plasma etching techniques.
According to a third embodiment of a material having a conductive pattern, according to the present invention, the patterned surface is planar and is the surface of the support or a patternwise treated continuous layer. The patterning of the continuous layer or the support can, for example, be realized by patternwise treatment with an electron beam, ion implantation, a corona discharge or a glow discharge.
According to a fourth embodiment of a material having a conductive pattern, according to the present invention, the patterned surface is planar and is a continuous layer which is patternwise treated with a corona discharge or a glow discharge.
According to a fifth embodiment of a material having a conductive pattern, according to the present invention, the patterned surface is non-planar and consists of a non-continuous layer provided on a continuous layer or on the support. The non-continuous layer can be produced using conventional printing techniques, such as screen printing, offset printing, flexographic printing and ink jet printing, with conventional resist technology, plasma etching techniques.
According to a sixth embodiment of a material having a conductive pattern, according to the present invention, the conductive element has a surface resistance lower than 106 xcexa9/square.
According to a seventh embodiment of a material having a conductive pattern, according to the present invention, the conductive element has a surface resistance lower than 104 xcexa9/square.
According to an eighth embodiment of a material having a conductive pattern, according to the present invention, the conductive element has a surface resistance capable of being lower than 106 xcexa9/square after treatment in a so-called conductivity enhancement process.
According to a ninth embodiment of a material having a conductive pattern, according to the present invention, the conductive element further contains a multidiazonium salt, a resin comprising a diazonium salt or both a multidiazonium salt and a resin comprising a diazonium salt, which reduces the removability of those parts of the conductive element contiguous with the patterned surface not removed during the development step. Combinations of resins comprising a diazonium salt can also be used.
Aspects of the present invention are realized by a material for making a conductive pattern, the material comprising a support and a conductive element, the conductive element containing a polyanion and an intrinsically conductive polymer, characterized in that one surface of the conductive element is an outermost surface of the material, the other surface of the conductive element is contiguous with a patterned surface, the patterned surface consisting of at least two types of surface element, and those arts of the conductive element contiguous with one type of surface element are capable of being at least partially removed by a developer. The term patterned surface, according to the material for making a conductive pattern, according to the present invention, means a surface with at least two types of surface elements exhibiting different abilities to adhere to the contiguous conductive element. This variation in the ability of elements of the surface to adhere to the contiguous conductive element over the patterned surface forms a pattern.
According to a first embodiment of a material for making a conductive pattern, according to the present invention, the conductive pattern is an electroconductive pattern.
According to a second embodiment of a material for making a conductive pattern, according to the present invention, the patterned surface is planar or non-planar. A non-planar pattern can be produced using conventional printing techniques, such as screen printing, offset printing, flexographic printing and ink jet printing, with conventional resist technology, plasma etching techniques.
According to a third embodiment of a material for making a conductive pattern, according to the present invention, the patterned surface is planar and is the surface of the support or a patternwise treated continuous layer. The patterning of the continuous layer or the support can, for example, be realized by patternwise treatment with an electron beam, ion implantation, a corona discharge or a glow discharge.
According to a fourth embodiment of a material for making a conductive pattern, according to the present invention, the patterned surface is a continuous layer which is patternwise treated with a corona discharge or a glow discharge.
According to a fifth embodiment of a material for making a conductive pattern, according to the present invention, the patterned surface is non-planar and consists of a non-continuous layer provided on a continuous layer or on the support. The non-continuous layer can be produced using conventional printing techniques, such as screen printing, offset printing, flexographic printing and ink jet printing, with conventional resist technology, plasma etching techniques.
According to a sixth embodiment of a material for making a conductive pattern, according to the present invention, the conductive element further contains an element which upon light exposure produces changes in the properties or composition of the exposed parts of the element.
Examples of such changes in the properties or composition of the exposed parts of the element are exposure-induced crosslinking; exposure-induced decrease of solubility; and exposure-induced increase of adhesion to the patterned surface of the non-removed parts of the conductive element.
According to a seventh embodiment of a material for making a conductive pattern, according to the present invention, the conductive element has a surface resistance lower than 106 xcexa9/square.
According to an eighth embodiment of a material for making a conductive pattern, according to the present invention, the conductive element has a surface resistance lower than 104 xcexa9/square.
A conductive pattern can be rendered electroconductive by a post-treatment process, such as a conductivity enhancement process. According to a ninth embodiment of a material for making a conductive pattern, according to the present invention, the conductive element has a surface resistance capable of being lower than 106 xcexa9/square after treatment in a so-called conductivity enhancement process.
The term xe2x80x9cconductivexe2x80x9d is related to the electric resistance of the material. The electric resistance of a layer is generally expressed in terms of surface resistance Rs (unit xcexa9; often specified as xcexa9/square). Alternatively, the conductivity may be expressed in terms of volume resistivity Rv=Rsxc2x7d, wherein d is the thickness of the layer, volume conductivity kv=1/Rv [unit: S(iemens)/cm] or surface conductance ks=1/Rs [unit: S(iemens).square].
All values of electric resistance presented herein are measured according to one of the following methods. In the first method the support coated with the electroconductive outermost layer is cut to obtain a strip having a length of 27.5 cm and a width of 35 mm and strip electrodes are applied over its width at a distance of 10 cm perpendicular to the edge of the strip. The electrodes are made of an intrinsically conductive polymer, ECCOCOAT CC-2 available from Emerson and Cumming Speciality polymers. Over the electrode a constant potential is applied and the current flowing through the circuit is measured on a pico-amperometer KEITHLEY 485. From the potential and the current, taking into account the geometry of the area between the electrodes, the surface resistance in xcexa9/square is calculated.
In the second method, the surface resistance was measured by contacting the outermost layer with parallel copper electrodes each 35 mm long and 35 mm apart capable of forming line contacts, the electrodes being separated by a teflon insulator. This enables a direct measurement of the surface resistance.
Supports for use according to the present invention include polymeric films, silicon, ceramics, oxides, glass, polymeric film reinforced glass, glass/plastic laminates, metal/plastic laminates, paper and laminated paper, optionally treated, provided with a subbing layer or other adhesion promoting means to aid adhesion to the light-exposure differentiable element. Suitable polymeric films are poly(ethylene terephthalate), poly(ethylene naphthalate), polystyrene, polyethersulphone, polycarbonate, polyacrylate, polyamide, polyimides, cellulosetriacetate, polyolefins and polyvinylchloride, optionally treated by corona discharge or glow discharge or provided with a subbing layer.
The conductive element used in the material of the present invention contains an intrinsically conductive polymer and can consist of one or more continuous layers.
The intrinsically conductive polymers used in the present invention can be any intrinsically conductive polymer known in the art e.g. polyacetylene, polypyrrole, polyaniline, polythiophene, etc. Details about suitable intrinsically conductive polymers can be found in textbooks, such as xe2x80x9cAdvances in Synthetic Metalsxe2x80x9d, ed. P. Bernier, S. Lefrant, and G. Bidan, Elsevier, 1999; xe2x80x9cIntrinsically Conducting Polymers: An Emerging Technologyxe2x80x9d, Kluwer (1993); xe2x80x9cConducting Polymer Fundamentals and Applications, A Practical Approachxe2x80x9d, P. Chandrasekhar, Kluwer, 1999; and xe2x80x9cHandbook of Organic Conducting Molecules and Polymersxe2x80x9d, Ed. Walwa, Vol. 1-4, Marcel Dekker Inc. (1997).
According to a tenth embodiment of the material having a conductive pattern, according to the present invention, or a tenth embodiment or the material for making a conductive pattern, according to the present invention, the intrinsically conductive polymer is a polyanion and a polymer or copolymer of a substituted or unsubstituted thiophene.
According to an eleventh embodiment of the material having a conductive pattern, according to the present invention, or an eleventh embodiment or the material for making a conductive pattern, according to the present invention, the intrinsically conductive polymer is a substituted or unsubstituted thiophene represented by formula (I): 
in which n is larger than 1 and each of R1 and R2 independently represents hydrogen or an optionally substituted C1-4 alkyl group or together represent an optionally substituted C1-4 alkylene group or an optionally substituted cycloalkylene group, preferably an ethylene group, an optionally alkyl-substituted methylene group, an optionally C1-12 alkyl- or phenyl-substituted ethylene group, a 1,3-propylene group or a 1,2-cyclohexylene group.
The preparation of such a polythiophene and of aqueous dispersions containing such a polythiophene and a polyanion is described in EP-A-440 957 and corresponding U.S. Pat. No. 5,300,575. Basically the preparation of polythiophene proceeds in the presence of polymeric polyanion compounds by oxidative polymerisation of 3,4-dialkoxythiophenes or 3,4-alkylenedioxythiophenes according to the following formula: 
wherein R1 and R2 are as defined above.
Stable aqueous polythiophene dispersions having a solids content of 0.05 to 55% by weight and preferably of 0.1 to 10% by weight can be obtained by dissolving thiophenes corresponding to the formula above, a polyacid and an oxidising agent in an organic solvent or preferably in water, optionally containing a certain amount of organic solvent, and then stirring the resulting solution or emulsion at 0xc2x0 C. to 100xc2x0 C. until the polymerisation reaction is completed. The polythiophenes formed by the oxidative polymerisation are positively charged, the location and number of such positive charges being not determinable with certainty and therefore not mentioned in the general formula of the repeating units of the polythiophene polymer.
The oxidising agents are those which are typically used for the oxidative polymerisation of pyrrole as described in for example J. Am. Soc. 85, 454 (1963). Preferred inexpensive and easy-to-handle oxidising agents are iron(III) salts, e.g. FeCl3, Fe(ClO4)3 and the iron(III) salts of organic acids and inorganic acids containing organic residues. Other suitable oxidising agents are H2O2, K2Cr2O7, alkali or ammonium persulphates, alkali perborates, potassium permanganate and copper salts such as copper tetrafluoroborate. Air or oxygen can also be used as oxidising agents. Theoretically, 2.25 equivalents of oxidising agent per mol of thiophene are required for the oxidative polymerisation thereof (J. Polym. Sci. Part A, Polymer Chemistry, Vol. 26, p. 1287, 1988). In practice, however, the oxidising agent is used in excess, for example, in excess of 0.1 to 2 equivalents per mol of thiophene.
The polyacid forms a polyanion or, alternatively, the polyanion can be added as a salt of the corresponding polyacids, e.g. an alkali salt. Preferred polyacids or salts thereof are polymeric carboxylic acids such as poly(acrylic acid), poly((meth)acrylic acid) and poly(maleic acid) or polymeric sulphonic acids such as poly(styrene sulphonic acid) or poly(vinyl sulphonic acid). Alternatively, copolymers of such carboxylic and/or sulphonic acids and of other polymerizable monomers such as styrene or acrylates can be used.
According to a twelfth embodiment of the material having a conductive pattern, according to the present invention, or a twelfth embodiment or the material for making a conductive pattern, according to the present invention, the polyanion is poly(styrenesulphonate).
The molecular weight of these polyanion forming polyacids is preferably between 1000 and 2xc3x97106, more preferably between 2000 and 5xc3x97105. These polyacids or their alkali salts are commercially available and can be prepared according to the known methods, e.g. as described in Houben-Weyl, Methoden der Organische Chemie, Bd. E20 Makromolekulare Stoffe, Teil 2, (1987), pp. 1141.
In the materials having a conductive pattern and for making a conductive pattern, according to the present invention, the conductive element, surface elements and layers of the material, according to the present invention, may contain a binder.
According to a thirteenth embodiment of the material having a conductive pattern, according to the present invention, or a thirteenth embodiment or the material for making a conductive pattern, according to the present invention, the conductive element further contains a binder, e.g. polyvinyl alcohol and a vinylidene chloride, methyl methacrylate, itaconic acid (88/10/2) terpolymer.
According to a fourteenth embodiment of a material having a conductive pattern, according to the present invention, the type A surface element has an outermost layer with respect to the support containing a proteinaceous binder e.g. gelatin, casein, collagen, albumin, keratin, gluten, zein and modified gelatin e.g. acetylated or phthaloyl gelatin.
According to a fifteenth embodiment of a material having a conductive pattern, according to the present invention, the type A surface element has an outermost layer with respect to the support containing gelatin.
According to a sixteenth embodiment of a material having a conductive pattern, according to the present invention, the type B surface element has an outermost layer with respect to the support which is exclusive of a proteinaceous binder and contains an optionally corona or glow discharge treated polymer containing a monomeric unit selected from the group consisting of acrylates e.g. ethyl acrylate, acrylic acid, ethylene, ethylene glycol, formaldehyde, itaconic acid, melamine, methacrylates e.g. methyl methacrylate, methacrylic acid, optionally substituted isophthalic acid e.g. 5-sulpho-isophthalic acid and isophthalic acid, optionally substituted terephthalic acid e.g. terephthalic acid and vinylidene chloride. Examples of suitable polymers for the outermost layer of type B surface element are:
Suitable binders for use in the material for making a conductive pattern, according to the present invention, are described in EP-A 564 911 and include water-soluble polymers, such as poly(vinyl alcohol), water-soluble homo- and co-polymers of acrylic acid and homo- and co-polymers of methacrylic acid, and polymer latexes. Preferred binders include poly(vinyl alcohol) and homo- and co-polymers of hydroxyethyl methacrylate and copolymers of 2-propenoic acid 2-phosphonooxy)ethyl ester, copolymers of 2-methyl-2-propenoic acid 2-phosphonooxy)ethyl ester. Such binders may be treated with a hardening agent, e.g. an epoxysilane such as 3-glycidyloxypropyltrimethoxysilane as described in EP-A 564 911, which is especially suitable when coating on a glass substrate.
According to a fourteenth aspect of the material for making a conductive pattern, according to the present invention, the outermost layer with respect to the support of the type of surface element capable of being at least partially removed by a developer is corona or glow discharge treated polyethylene terephthalate.
According to a fifteenth aspect of the material for making a conductive pattern, according to the present invention, the outermost layer with respect to the support of the type of surface element capable of being at least partially removed by a developer contains polyethylene or a melamine-formaldehyde resin.
Examples of suitable polymers for use in the outermost layer with respect to the support of the type of surface element capable of being at least partially removed by a developer are: polyethylene terephthalate surface treated with a corona discharge or with a glow discharge, polyethylene, e.g. HORDAMER(trademark) PE02, and melamine-formaldehyde resin, e.g. PAREZ RESINS(trademark) 613.
According to a sixteenth aspect of the material for making a conductive pattern, according to the present invention, the outermost layer with respect to the support of the type of surface element not capable of being at least partially removed by a developer contains a polymer latex.
According to a seventeenth aspect of the material for making a conductive pattern, according to the present invention, the outermost layer with respect to the support of the type of surface element not capable of being at least partially removed by a developer contains a polymer containing a monomer unit selected from the group consisting of acrylates, acrylic acid, itaconic acid, methacrylates, methacrylic acid and vinylidene chloride.
According to an eighteenth aspect of the material for making a conductive pattern, according to the present invention, the outermost layer with respect to the support of the type of surface element not capable of being at least partially removed by a developer contains a polymer containing a monomer unit selected from the group consisting of ethylene glycol, optionally substituted isophthalic acid e.g. isophthalic acid and 5-sulpho-isophthalic acid, and optionally substituted terephthalic acid.
Examples of suitable polymers for use in the outermost layer with respect to the support of the type of surface element not capable of being at least partially removed by a developer are: LATEX01, LATEX02 and LATEX03.
The conductive element, surface elements and any layers of the material, according to the present invention, may contain various additional ingredients, such as one or more binders, one or more surfactants, spacing particles, UV-acutance compounds and IR-absorbers.
According to a seventeenth embodiment of the material having a conductive pattern, according to the present invention, or a nineteenth embodiment of the material for making a conductive pattern, according to the present invention, the conductive element contains at least one anionic or non-ionic surfactant.
According to an eighteenth embodiment of the material having a conductive pattern, according to the present invention, or a twentieth embodiment of the material for making a conductive pattern, according to the present invention, the conductive element contains at least one non-ionic surfactant selected from the group of surfactants consisting of ethoxylated/fluroralkyl surfactants, polyethoxylated silicone surfactants, polysiloxane/polyether surfactants, ammonium salts of perfluro-alkylcarboxylic acids, polyethoxylated surfactants and fluorine-containing surfactants.
According to a nineteenth embodiment of the material having a conductive pattern, according to the present invention, or a twenty-first embodiment or the material for making a conductive pattern, according to the present invention, at least one type of the surface element contains at least one anionic or non-ionic surfactant.
Suitable non-ionic surfactants are:
Suitable anionic surfactants are:
A multidiazonium salt is a salt with at least two groups with two nitrogen atoms bonded together with a double or triple bond, such groups including xe2x80x94Nxe2x89xa1N+ and xe2x80x94Nxe2x95x90Nxe2x80x94R groups, e.g. xe2x80x94Nxe2x95x90Nxe2x80x94SO3M groups e.g. bisdiazonium salts, trisdiazonium salts, tetrakisdiazonium salts, bis(aryldiazosulphonate) salts, tris(aryldiazosulphonate) salt and terakis(bis(aryldiazosulphonate) salts.
Upon exposure the adhesion of a conductive element containing a multidiazonium salt to the patterned surface is increased (due to the destruction of the diazonium groups) and additionally the photolysis products of the diazo may increase the level of crosslinking of the polymeric binder or resin comprising a multidiazonium salt if present. Combinations of multidiazonium salts can also be used.
Bisdiazonium salts for use in the material for making a conductive pattern, according to the present invention, include: benzidine tetrazoniumchloride, 3,3xe2x80x2-dimethylbenzidine tetrazoniumchloride, 3,3xe2x80x2-dimethoxybenzidine tetrazoniumchloride, 4,4xe2x80x2-diaminodiphenylamine tetrazoniumchloride, 3,3xe2x80x2-diethylbenzidine tetrazoniumsulphate, 4-aminodiphenylamine diazoniumsulphate, 4-aminodiphenylamine diazoniumchloride, 4-piperidino aniline diazoniumsulphate, 4-diethylamino aniline diazoniumsulphate and oligomeric condensation products of diazodiphenylamine and formaldehyde.
According to a twenty-second embodiment of a material for making a conductive pattern, according to the present invention, the conductive element further contains a multidiazonium salt, a resin comprising a diazonium salt or both a multidiazonium salt and a resin comprising a diazonium salt, which reduces the removability of those parts of the conductive element contiguous with the patterned surface not removed during the development step. Combinations of resins comprising a diazonium salt can also be used.
According to a twenty-third embodiment of the material for making a conductive pattern, according to the present invention, the conductive element contains a bis(aryldiazosulphonate) salt, a tris(aryldiazosulphonate) salt or a tetrakis(aryldiazosulphonate) salt.
According to a twenty-fourth embodiment of the material for making a conductive pattern, according to the present invention, the conductive element further contains a bis(aryldiazosulphonate) salt, which reduces the removability of exposed parts of the outermost layer, according to formula (II):
xe2x80x83MO3Sxe2x80x94Nxe2x95x90Nxe2x80x94Arxe2x80x94Lxe2x80x94Arxe2x80x94Nxe2x95x90Nxe2x80x94SO3Mxe2x80x83xe2x80x83(II)
where Ar is a substituted or unsubstituted aryl group, L is a divalent linking group, and M is a cation. L preferably represents a substituted or unsubstituted divalent aryl group or a substituted or unsubstituted saturated or unsaturated alkylene group, whose chain is optionally substituted with at least one of an oxygen atom, a sulphur atom or a nitrogen atom. Ar preferably represents an unsubstituted phenyl group or a phenyl group substituted with one or more alkyl groups, aryl groups, alkoxy groups, aryloxy groups or amino groups. M preferably represents a cation such as NH4+ or a metal ion such as a cation of Al, Cu, Zn, an alkaline earth metal or alkali metal.
The term resin comprising a diazonium salt means a resin with groups with two nitrogen atoms bonded together with a double or triple bond, such groups including xe2x80x94Nxe2x89xa1N+ and xe2x80x94Nxe2x95x90Nxe2x80x94R groups e.g. xe2x80x94Nxe2x95x90Nxe2x80x94SO3M groups. Suitable resins comprising a diazonium salt, according to the present invention, include polymers or copolymers of an aryldiazosulphonate and condensation products of an aromatic diazonium salt. Such condensation products are described, for example, in DE-P-1 214 086.
Upon exposure the conductive element containing resins comprising a diazonium salt exhibits increased adhesion to the patterned surface and additionally the photolysis products of the diazo may increase the level of crosslinking of the polymeric binder or resin comprising a diazonium salt.
According to a twenty-fifth embodiment of the material for making a conductive pattern, according to the present invention, the conductive element further contains a polymer or copolymer of an aryldiazosulphonate.
According to a twenty-sixth embodiment of the material for making a conductive pattern, according to the present invention, the conductive element further contains a polymer or copolymer of an aryldiazosulphonate represented by formula (III): 
wherein R0, R1 and R2 each independently represent hydrogen, an alkyl group, a nitrile or a halogen, e.g. Cl, L represents a divalent linking group, n represents 0 or 1, A represents an aryl group and M represents a cation. L preferably represents divalent linking group selected from the group consisting of: xe2x80x94(X)txe2x80x94CONR3xe2x80x94, xe2x80x94(X)txe2x80x94COOxe2x80x94, xe2x80x94Xxe2x80x94 and xe2x80x94(X)txe2x80x94COxe2x80x94, wherein t represents 0 or 1; R3 represents hydrogen, an alkyl group or an aryl group; X represents an alkylene group, an arylene group, an alkylenoxy group, an arylenoxy group, an alkylenethio group, an arylenethio group, an alkylenamino group, an arylenamino group, oxygen, sulphur or an aminogroup. A preferably represents an unsubstituted aryl group, e.g. an unsubstituted phenyl group or an aryl group, e.g. phenyl, substituted with one or more alkyl groups, aryl groups, alkoxy groups, aryloxy groups or amino groups. M preferably represents a cation such as NH4+ or a metal ion such as a cation of Al, Cu, Zn, an alkaline earth metal or alkali metal.
Polymers and copolymers of an aryldiazosulphonate can be prepared by homo- or copolymerization of aryldiazosulphonate monomers with other aryldiazosulphonate monomers and/or with vinyl monomers such as (meth)acrylic acid or esters thereof, (meth)acrylamide, acrylonitrile, vinylacetate, vinylchloride, vinylidene chloride, styrene, alpha-methyl styrene etc. A particularly preferred comonomer is hydroxyethylmethacrylate. Specific examples of suitable aryldiazosulphonate polymers are described in EP-A 771 645.
According to a twenty-seventh embodiment of the material for making a conductive pattern, according to the present invention, the conductive element further contains a combination of a resin comprising an aryldiazosulphonate and a bis(aryldiazosulphonate) salt.
According to a twenty-eighth embodiment of the material for making a conductive pattern, according to the present invention, the conductive element further contains a combination of a resin comprising an aryldiazosulphonate and a bis(aryldiazosulphonate) salt in the molar percentage ratio range of 60%/40% to 10%/90%.
According to a twenty-ninth embodiment of the material for making a conductive pattern, according to the present invention, the conductive element further contains a combination of a resin comprising an aryldiazosulphonate and a bis(aryldiazosulphonate) salt in the molar percentage ratio range of 50%/50% to 20%/80%.
According to a thirieth embodiment of the material for making a conductive pattern, according to the present invention, the conductive element further contains a combination of a copolymer of hydroxyethylmethacrylate and sodium-4-methacryloyl-aminophenyl-diazo-sulphonate and a bis (aryldiazosulphonate) salt.
In the production of the materials of the present invention, the coating dispersions or solutions may be applied by any means known in the art: they can be spin-coated, sprayed or coated by any of the continuous coating techniques that are used to coat solutions on continuous webs, e.g. dip coating, rod coating, blade coating, air knife coating, gravure coating, reverse roll coating, extrusion coating, slide coating and curtain coating. An overview of these coating techniques can be found in the book xe2x80x9cModern Coating and Drying Technologyxe2x80x9d, Edward Cohen and Edgar B. Gutoff Editors, VCH publishers, Inc, New York, N.Y., 1992. It is also possible to coat simultaneously multiple layers by coatings technique such as slide coating and curtain coating. It is also possible to apply the coating solutions and dispersions by printing techniques, e.g., ink-jet printing, gravure printing, flexo printing, or offset printing.
The coating solution or dispersion containing the intrinsically conductive polymer is preferably applied to the substrate in such an amount that the coated polymer layer contains between 10 and 5000 mg of intrinsically conductive polymer per m2, more preferably between 100 and 500 mg of intrinsically conductive polymer per m2.
The coating dispersion or solution of a polyanion and an intrinsically conductive polymer of the conductive element preferably also comprises an organic compound that is: a linear, branched or cyclic aliphatic C2-20 hydrocarbon or an optionally substituted aromatic C6-14 hydrocarbon or a pyran or a furan, the organic compound comprising at least two hydroxy groups or at least one xe2x80x94COX or xe2x80x94CONYZ group wherein X denotes xe2x80x94OH and Y and Z independently of one another represent H or alkyl; or a hetero-cyclic compound containing at least one lactam group. Examples of such organic compounds are e.g. N-methyl-2-pyrrolidinone, 2-pyrrolidinone, 1,3-dimethyl-2-imidazolidone, N,N,Nxe2x80x2,Nxe2x80x2-tetramethyl-urea, formamide, dimethylformamide, and N,N-dimethylacetamide. Preferred examples are sugar or sugar derivatives such as arabinose, saccharose, glucose, fructose and lactose, or di- or polyalcohols such as sorbitol, xylitol, mannitol, mannose, galactose, sorbose, gluconic acid, ethylene glycol, di- or tri(ethylene glycol), 1,1,1-trimethylol-propane, 1,3-propanediol, 1,5-pentanediol, 1,2,3-propantriol, 1,2,4-butantriol, 1,2,6-hexantriol, or aromatic di- or polyalcohols such as resorcinol.
Subsequent to processing the material of the present invention with a developer to remove at least partially those parts of the conductive element contiguous with one type of surface elements, the material of the present invention can be exposed to ultraviolet light optionally in combination with blue light in the wavelength range of 250 to 500 nm or infrared light. Useful exposure sources are high or medium pressure halogen mercury vapour lamps, e.g. of 1000 W or lasers having an emission wavelength in the range from about 700 to about 1500 nm, such as a semiconductor laser diode, a Nd:YAG laser or a Nd:YLF laser.
The material of the present invention is developed in a developer which can be deionized water or is preferably water-based. During development those parts of the conductive element contiguous with one type of surface elements of the patterned surface are at least partially removed and a conductive pattern is thereby obtained. Suitable aqueous developers are deionized water, AZ303 (Clariant) or EN232 (AGFA-GEVAERT N.V.). When a subbing layer (also called substrate layer) is present on the support the material is preferably rubbed thoroughly with a tissue during development to avoid residual conductivity. The rubbing can be done in the processing fluid or in a separate water bath after the development stage. Similar results can be obtained by applying a high pressure water jet after the development stage, thereby avoiding contact with the conductive areas. Alternatively, if conductivity enhancement is necessary, the developer can contain the conductivity enhancement agent, thereby combining the steps of development and contact with the conductivity enhancement agent.
The conductive pattern obtained by the method of the present invention can be used as an electronic circuit for making an electric or semiconductor device such as a printed circuit board, an integrated circuit, a display, an electroluminescent device or a photovoltaic cell. The patterned electrode obtained by the method of the present invention can also be used for screening electromagnetic radiation or earthing electric charges, for making touch screens, radio frequency identification tags, electrochromic windows and in imaging systems, e.g. silver halide photography or electrophotography. Also a device such as the electronic book described in WO 97/04398 may particularly benefit from the flexible electrode of the present invention. Even more applications are described in WO 97/18944.